Fisheries: Impacts & Prospects
Fish consumption around the world has doubled in the last 50 years, reaching about 7% of the share of global protein intake. Fish is also central to the nutrition and economy of developing countries, with 540 million people depending on fish production for their livelihoods, and coastal and riverine communities in Southeast Asia and West Africa getting over 50% of their protein from fish (FAO 2016).
Fisherman in Ghana, one of the countries most reliant on fish (©Tomaszewski).
To supply this rising demand of fish from a growing population, commercial fisheries have been increasing their catches, resulting in 1/3 of wild fish stocks being reduced to biologically unsustainable levels (at lower abundance than their maximum sustainable yield (MSY) that they need to recover), a threefold increase in the past 50 years. Additionally, about 60% of stocks are fished at their MSY and are highly vulnerable to becoming unsustainable.
Overfishing causes the direct loss of the targeted species, but affects their entire ecosystems. Destructive fishing gear such as dredging or bottom trawling (Video 1) causes dramatic habitat losses comparable to deforestation. Moreover, the selective fishing of certain species alters the structure and composition of marine communities. And the by-catch of non-targeted top predators in fishing nets (Video 2) causes trophic cascades, a domino effect affecting the whole marine food web.
Video 1 - Animation of bottom trawling (for other fishing techniques, click here).
Video 2 - Animation of gillnetting.
What is the path towards sustainable fishing then? First, it is necessary to reduce the overcapacity of the global fishing fleet and eliminate these destructive industrial fishing practices to avoid depletion of stocks and secure the future of fishing. ‘Fishing down marine food webs’ (targeting species in low ranks of the food web) has also been proposed to reduce the cascading effects from declining predator populations, but this may still have some adverse effects such as simplifying food webs. The establishment of marine-protected areas is also urged, especially with the expansion of international fisheries into remote and fragile areas such as deep waters and the Arctic. And finally, stronger international regulations are needed to stop illegal fishing by commercial fisheries that compete against local fishermen for their resources.
Diego Garcia-Vega - Novembre 19th 2017